Pressure-activated trap primer valve

ABSTRACT

A pressure activated trap primer valve for drain traps includes an expansion chamber with a piston between the compressible air and water. The piston prevents waterlogging of the expansion chamber to reduce maintenance of the trap primer valve. The trap primer valve also includes an inlet pipe coaxially configured in the expansion chamber. The inlet pipe is operably connected to a chamber below the expansion chamber which is closed at the bottom by a diaphragm. The diaphragm in a relaxed, undeflected position closes an outlet that drains to the trap. A chamber below the diaphragm is replenished by the expansion chamber. When pressure in the supply pipe and inlet pipe decreases, such as when a faucet is opened, the diaphragm deflects. Deflecting the diaphragm opens the outlet, allowing a limited amount of water to flow out of the chamber and into the trap. The intermittent water flow to the trap ensures a minimum volume for maintaining a gas tight seal in the trap. As trap primer valve pressures reach equilibrium, the diaphragm returns to an undeflected position, sealing the outlet again.

BACKGROUND

The present invention relates to plumbing systems and components andmore particularly, to trap primer valves which supply a minimal flow ofwater to keep drain traps from drying out. Drain traps are configured toretain water which prevents sewer line gases from rising through thesewer lines and into buildings. Sewer gases are not only offensive, butconcentrated in a closed space with an ignition source, they canexplode. Drain traps keep noxious gases from occupied areas and preventthe possibility of explosion.

In homes and buildings, traps are generally located below and close toeach drain, and generally have a U-shaped configuration with an inlet onone arm and an outlet on the other arm, the outlet being lower than theinlet. The bottom of the ‘U’ is filled with water to the level of theoutlet and seals the trap. In situations where the drain only getsintermittent use, the trap water can evaporate, allowing gases to flowup the drain pipe and into buildings. The trap primer valve introducesintermittent water flows, maintaining a seal regardless of how often itis used and ensures the trap continues to function.

There are a variety of trap primer valves available, some haveprocessors and electronic valves that determine time and duration offlow to the traps. Some trap primer valves have a diaphragm or pistonacting as a valve component, so that when there is a drop in linepressure, the diaphragm or piston is displaced, permitting a limitedflow of water. These primers often use an expansion chamber to provide apressure differential across the diaphragm or piston and supply thewater for the flow.

The expansion chambers of trap primer valves with this configurationhave the opposite problem of the drain trap. The air above the water inthe expansion chamber can be slowly absorbed by the water. Absorbing allthe air in the expansion chamber is known as “waterlogging.” Theexpansion chamber works by increasing or decreasing the volume of aclosed air chamber, compressing and decompressing the air in response tovariations in line pressure. With no air in the chamber, the primercan't function properly, and once a trap primer valve becomeswaterlogged, it has to be repaired by removing it from the supply line,draining it and returning it to service.

There is a need for a vacuum-operated trap primer valve to supply draintraps with water that does not become waterlogged and accordingly doesnot require maintenance to recharge the expansion chamber.

SUMMARY OF THE INVENTION

The present invention is directed to a trap primer valve including avalve housing and piston slidably supported in the housing and sealedtherewithin to provide separable air and water chambers. Thisconstruction prevents air in the air chamber from being absorbed by thewater which; over time, would fill the air chamber.

The exemplary trap primer valve of the present invention is activated byvariation in pressure in the supply line to which it is attached. Thetrap primer valve includes a housing with an inlet that attaches to asupply line and an outlet that runs to a trap. The housing is dividedinto upper and lower sections by a plate. The upper section is anexpansion chamber with trapped air and water.

The inlet pipe runs vertically through the upper section expansionchamber and is operably connected to the lower section. The air andwater in the upper section expansion chamber are separated by a pistonwhich is tightly sealed against the housing walls and the inlet pipe.The piston slides vertically in response to changes in water pressuremaintaining equal pressure in the water below the piston and the airabove the piston.

The lower section of the valve is separated into upper and lowerchambers by a diaphragm. The upper chamber is connected to the supplyline by the inlet pipe that passes through the upper section, and ismaintained at the same pressure as the inlet pipe and supply line. Theupper chamber of the lower section is connected to the expansion chamberby a check valve in the dividing plate that allows water to flow fromthe upper chamber into the expansion chamber.

The lower chamber is defined by the diaphragm and a base directly belowthe diaphragm. The diaphragm is operably connected to the outlet formedin the base. The outlet is open or shut depending on whether thediaphragm is deflected or undeflected, respectively. The lower chamberis supplied with water from the expansion chamber by channels formed inthe rim of the base.

The outlet is open only when the inlet pipe pressure drops. As the inletpressure drops, the pressure in the chamber above the diaphragm dropsand the check valve in the plate between the expansion chamber and upperchamber closes because the air in the expansion chamber is still at thehigher pressure. Water cannot flow from the expansion chamber into theupper chamber with the valve closed.

The pressure drop in the chamber above the diaphragm causes thediaphragm to deflect or rise due to the pressure differential above andbelow the diaphragm. Deflecting the diaphragm opens the outlet andallows water to flow out from the lower chamber and downwardly into theoutlet pipe. As water flows out of the chamber below the diaphragm, thepressure drops, the diaphragm returns to the undeflected position as thepressure differential equalizes, again closing the outlet.

Water does flow from the expansion chamber, through the channels, to thelower chamber below the diaphragm to recharge the water lost to theoutlet. Without air in the expansion chamber, low pressure in the supplyline would close the check valve and a vacuum would form as water triedto flow out of the expansion chamber and the outlet.

The advantages of the present invention will be understood more readilyafter a consideration of the drawings and the Detailed Description ofthe Preferred Embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a plumbing system using a drain trapprimer valve of the present invention showing a supply line extendingthrough a wall, with an attached faucet at the end of the supply line, aprimer valve is shown attached to the supply line, a drain trap on theother side of the wall and a line connecting the primer valve to thedrain trap.

FIG. 2 is a cross sectional side view of the trap primer valve of thepresent invention with its diaphragm in an undeflected position therebyclosing the outlet, including a piston, a plate, a diaphragm and a base.

FIG. 3 is a cross sectional side view of the lower section of the trapprimer valve of FIG. 2 showing the diaphragm in a deflected positionthereby opening the outlet.

FIG. 4 is a top view of the base of FIG. 4 showing the channels alongthe top rim of the base.

FIG. 5 is a schematic view of a primer valve system similar to FIG. 1showing a faucet and the trap primer valve attached to a supply line,the trap primer valve including an inlet pipe, a diaphragm, a checkvalve, a piston and chambers.

FIG. 6 is a schematic view of the trap primer valve system of FIG. 5 inequilibrium.

FIG. 7 is a schematic view of the trap primer valve system of FIG. 5during a drop in supply line pressure which causes the diaphragm todeflect thereby, allowing flow from the outlet and water flowing to thelower chamber from the upper section, displacing the piston downwards.

FIG. 8 is a schematic view of the trap primer valve system of FIG. 5showing line pressure returning to normal and water flowing to the uppersection displacing the piston upwards.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the arrangement of a supply and drain system, generallyindicated at 10, including a supply pipe or supply line 12, a faucet 14,a primer drain 16, a trap 18 and the location of a trap primer valve 20constructed in accordance with the present invention. Trap 18 isconnected to drain D in floor F and supply pipe 12 supplies water orwater under pressure to faucet 14 which can be opened or closed by auser. Trap primer valve 20 is operable to meter or supply small volumesof water through primer drain 16 to trap 18, thereby to maintain watercontinuously in the trap. Trap primer valve 20 functions as a valvecontrolled by fluctuations in supply pipe pressure, as will bedescribed.

As shown in FIG. 2, trap primer valve 20 includes a housing 22, whichincludes a conical section 23 a and a cylindrical section 23 b, an inletpipe 24, an inlet connector 26, a slideable piston 27 including an innercircumference defined by a sleeve 28 and an outer circumferenceindicated at 29. A plate is shown at 30, a diaphragm at 32 and a base at34. Housing 22, including conical portion 23 a and cylindrical section23 b, along with inlet pipe 24, forms inner and outer coaxial tubes. Theinterior diameter of section 23 b is constant, so that piston 27 canslide up and down without binding. Plate 30 and base 34 are fixed inhousing 22 and retain diaphragm 32 between them. Diaphragm 32 is shownin FIG. 2 in a relaxed or undeflected position. Base 34 includes a drainpipe 36 and an outlet 37. The wall of drain pipe 36 may have ports orperforations 38 to prevent a vacuum in drain pipe 36.

Piston 27 with inside circumference 28 and outside circumference 29 forman annular ring or disk. Inside circumference 28 forms a sleeve thatholds an inner seal or O-ring 39, compressed to form a seal betweeninlet pipe 24 and the inner circumference of piston 27. Outercircumference 29 holds an outer seal or O-ring 40 which is compressed toform a seal between outer circumference 29 and the inner wall ofcylindrical section 23 b. Piston 27 with O-rings 39 and 40 prevent airfrom being absorbed in the water below piston 27. If water werepermitted to be absorbed, trap primer valve 20 eventually could fail.

Base 34 and diaphragm 32 define a lower chamber 100 and an upper chamber200 above the diaphragm. Housing 22, inlet pipe 24, piston 27 and plate30 define a water chamber 300. An air chamber 400 above piston 27 isdefined by housing 22, inlet pipe 24 and piston 27. Expansion chamber500 includes water chamber 300, air chamber 400 and piston 27.

Plate 30 separates expansion chamber 500 from the lower section whichincludes chambers 100 and 200 and diaphragm 32. Plate 30 includes afirst stepped hole 46 to accommodate the end of pipe 24. Plate 30includes a second stepped hole 48 which forms valve 50. Valve 50 may bea ball check valve with means to retain the ball in the valve housing(not shown).

Plate 30 is retained in position in housing 22 by a step or shoulder 52.Plate 30 is sized to provide water flow between housing 22 and plate 30so water may flow from chamber 300 to channels 44 in base 34. Shoulder52 is configured to allow water flow around plate 30.

The upper surface of piston 27 faces air chamber 400 and its bottomsurface faces water chamber 300. As such, piston 27 slides up and downin response to pressure differentials between water chamber 300 and airchamber 400. Piston 27, plate 30, and base 34 may be manufactured fromany appropriate material such as nylon, ABS or a metal such as copper ora copper alloy. Housing 22 may also be manufactured from copper or acopper alloy.

Diaphragm 32 may be a disk manufactured from an appropriate materialsuch that it will flex appropriately under pressure. Diaphragm 32 mayvary in thickness from the center to the rim. It may have a thickenedrim. Diaphragm 32 may be thicker at the center than towards the rim.

Diaphragm 32 deflects when the pressure in chamber 200 drops below thepressure of chamber 100. FIG. 3 is a cross section of the lower part oftrap primer valve 20 showing diaphragm 32 in a deflected position causedby a reduction in pressure in chamber 200. Deflection of diaphragm 32uncovers outlet 37 allowing water to flow out from chamber 100. Airpressure in the chamber 400 urges piston 27 downwardly to force water inchamber 300 through channels 44 into chamber 100 and outwardly throughoutlet 37.

FIG. 4 is a top view of base 34 showing channels 44 along the rim ofbase 34. Base 34 includes drain pipe 36 and outlet 37. Base 34 haschannels 44 in the upper rim. Channels 44 permit water from chamber 300,passing between plate 30 and housing 22, to enter chamber 100.

When plate 30, diaphragm 32 and base 34 are assembled, diaphragm 32 iscompressed and is sealed against plate 30. Water is prevented fromflowing from chamber 200 to chamber 100 by diaphragm 32. Water may flowfrom chamber 300 above plate 30, between plate 30 and housing 22 andthrough channels 44 into chamber 100. Channels 44 may limit the rate offlow rate into chamber 100.

Operation of the Trap Primer Valve

The operation of the trap primer valve of the present invention isillustrated in the schematic view of FIGS. 5-8. FIG. 5 shows a supplysystem 60, similar to supply system 10 in FIG. 1, illustrating theoperation of trap primer valve 20. Shown in the schematic illustrationare supply line 12, faucet 14, trap 18 in floor F below drain D. Trapprimer valve 20 is operably connected to supply line 12 and connected todrain trap 18 by drain pipe 36. Inlet pipe 24 operably connects supplyline 12 to chamber 200. Chamber 200 includes diaphragm 32, outlet 37 andvalve 50.

Normal pressure in the following figures is the pressure in supply line12 with faucet 14 closed. Opening faucet 14 decreases pressure in supplyline 12. FIG. 6 shows supply system 60, at equilibrium with supply pipe12 and chamber 200 at normal pressure. Diaphragm 32 is undeflected andcloses outlet 37. Chambers 100, 300 and 400 are also at normal pressure,which is the pressure of supply line 12.

FIG. 7 shows primer system 60 as faucet 14 is opened by a user. Thepressure in supply line 12 drops as faucet 14 is opened. Pressure alsodrops in chamber 200, operably connected to supply pipe 12, valve 50closes and diaphragm 32 deflects upwardly with the reduced pressure inchamber 200. With diaphragm 32 deflected, outlet 37 is uncovered andwater from chamber 100 flows from outlet 37 to trap 18.

Flow from outlet 37 is enabled by air pressure in chamber 400. Chamber400 air pressure displaces piston 27 pushing on water in chamber 300 andcausing water flow around chamber 200 and into chamber 100. Without theair compressed in chamber 400, no flow would occur out of outlet 37.

FIG. 7 shows supply system 60 as faucet 14 is closed and pressure insupply line 12 returns to normal. The pressure in chamber 200 returns tonormal as well. Diaphragm 32 returns to its normal, undeflected positionclosing outlet 37. Because pressure in chamber 200 is now greater thanchambers 300 and 100, water flows from chamber 200 to chamber 300through valve 50. As chamber 300 pressure increases, piston 27 rises andcompresses air in chamber 400.

Trap primer valve 20 returns to equilibrium again with chambers 100,200, 300 and 400 at the same pressure as supply line 12 and outlet 37closed as represented in FIG. 8. As pressure drops again, the processwill be repeated.

Water is relatively incompressible and cannot store adequate pressureenergy to function in this configuration. Functioning of expansionchamber 500 prevents vapor lock and siphoning in trap primer valve 20.Expansion chamber 500 allows the pressure energy to be stored as airpressure in chamber 400 and released when it is required.

Outlet 37 may be configured with vacuum breaker port 38. Vacuum breakerport 38 ensures that water from trap 18 cannot be pulled into trapprimer valve 20 and contaminate the water supply. Any water coming backup primer drain 16 of FIG. 1 will flow out vacuum port 38 rather than upoutlet 37, which is of limited diameter.

These are examples and should not be construed as limitations. Anyconfiguration or combination of components presented which performs asimilar function should be considered as within the scope of thisdisclosure.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and subcombinations of the various elements, features,functions and/or properties disclosed herein. Similarly, where any claimrecites “a” or “a first” element or the equivalent thereof, such claimshould be understood to include incorporation of one or more suchelements, neither requiring nor excluding two or more such elements.

Inventions embodied in various combinations and subcombinations offeatures, functions, elements, and/or properties may be claimed throughpresentation of new claims in a related application. Such new claims,whether they are directed to a different invention or directed to thesame invention, whether different, broader, narrower or equal in scopeto the original claims, are also regarded as included within the subjectmatter of the inventions of the present disclosure.

1. A trap primer comprising a first section separated into an upper air chamber and a lower water chamber by a sliding piston configured to prevent air leaving the upper air chamber; a second section, below the first section, the second section divided into an upper chamber and a lower chamber by a diaphragm; an inflow pipe through the center of the first section to the upper chamber of the second section; and an outlet from the second section lower chamber with flow from the outlet controlled by the diaphragm; wherein the upper chamber of the second section is connected to the first section by a check valve; the lower chamber of the second section is supplied with water from the first section; and a drop in pressure at the inflow pipe raises the diaphragm, releasing water from the outlet.
 2. The trap primer of claim 1 where the sliding piston is sealed at inner and outer circumferences by o-rings.
 3. The trap primer of claim 1 where the check valve has a ball and a seat.
 4. An expansion chamber to be used in a trap primer valve, the expansion chamber comprising: a first inner coaxial tube configured to connect to a water supply line; a second outer coaxial tube which acts as a housing; a first, upper end of the expansion chamber, the upper end closed by joining the inner and outer tube; a second, lower end of the expansion chamber defined by a piston slidable between the inner and outer tube; wherein the expansion chamber is charged with a gas that acts on a first upper side of the piston; water pressure in the supply line acts on a second lower side of the piston; the piston is sealed to the inner and outer coaxial tubes; and displacing the piston changes the volume of the gas in the expansion chamber.
 5. The expansion chamber of claim 4 where the piston is sealed by o-rings at the inner and outer circumferences of the piston.
 6. The expansion chamber of claim 4 where the expansion chamber is part of a primer valve that operates as a function of changes in line pressure.
 7. The expansion chamber of claim 4 where the first and second coaxial tubes are composed of copper or copper alloy.
 8. The expansion chamber of claim 4 where the piston is composed of polyvinylchloride.
 9. A piston to be used in a closed expansion chamber including a water supply pipe comprising; an annular disk with a first inner circumference and a second outer circumference; a seal located at the first circumference that contacts the supply pipe; and a seal located at the second circumference that contacts an expansion chamber wall; wherein the piston divides the expansion chamber into a closed upper gas filled section and a lower water filled section; and differences in pressure between the upper filled gas section and the lower water filled section displaces the piston.
 10. The piston of claim 9 where the seals are o-rings.
 11. The piston of claim 9 where the annular disk is formed from polyvinylchloride. 